Too many white cells-TAM, JMML, or something else?

Leukocytosis is a common finding in pediatric patients, and the differential diagnosis can be broad, including benign reactive leukocytosis and malignant myeloproliferative disorders. Transient abnormal myelopoiesis is a myeloproliferative disorder that occurs in young infants with constitutional trisomy 21 and somatic GATA1 mutations. Most patients are observed, but outcomes span the spectrum from spontaneous resolution to life-threatening complications. Juvenile myelomonocytic leukemia is a highly aggressive myeloproliferative disorder associated with altered RAS-pathway signaling that occurs in infants and young children. Treatment typically involves hematopoietic stem cell transplantation, but certain patients can be observed. Early recognition of these and other myeloproliferative disorders is important and requires a clinician to be aware of these diagnoses and have a clear understanding of their presentations. This paper discusses the presentation and evaluation of leukocytosis when myeloproliferative disorders are part of the differential and reviews different concepts regarding treatment strategies.

Chronic Myeloid Leukaemia In A 14-Year-Old Child: An Unusual Case Report

Chronic myeloid leukaemia is a myeloproliferative stem cell disorder characterized by dysregulated production and proliferation of myeloid cells. Hallmark of the disease is the reciprocal translocation between chromosome 9 and 22 giving rise to an abnormal chromosome known as Philadelphia chromosome. Approximately 15% of all leukaemias are chronic myeloid leukaemia with a slight male predominance. This is a case of a 14-year-old boy with no premorbid presented with 4 months history of fatigue and shortness of breath on exertion. On examination patient was vitally stable. On general physical examination there was pallor and sternal tenderness. On abdominal examination spleen was palpable with a size of about 8cm. Respiratory, cardiovascular and musculoskeletal examination was unremarkable. Complete blood picture showed leukocytosis, low haemoglobin and normal platelets. Erythrocyte sedimentation rate was 65 mm/hr. Liver function tests, Renal function tests, Serum electrolytes, Urine routine examination and c-reactive protein were normal. Chest x-ray and Electrocardiography was normal. Peripheral blood smear showed neutrophils 56% with 3% lymphocytes, 1% blasts and retic count of 0.5%. Bone marrow biopsy was suggestive of chronic myeloid leukaemia which was confirmed by FISH and Cytogenetic studies.

A homozygous stop-gain variant in ARHGAP42 is associated with childhood interstitial lung disease, systemic hypertension, and immunological findings

ARHGAP42 encodes Rho GTPase activating protein 42 that belongs to a member of the GTPase Regulator Associated with Focal Adhesion Kinase (GRAF) family. ARHGAP42 is involved in blood pressure control by regulating vascular tone. Despite these findings, disorders of human variants in the coding part of ARHGAP42 have not been reported. Here, we describe an 8-year-old girl with childhood interstitial lung disease (chILD), systemic hypertension, and immunological findings who carries a homozygous stop-gain variant (c.469G>T, p.(Glu157Ter)) in the ARHGAP42 gene. The family history is notable for both parents with hypertension. Histopathological examination of the proband lung biopsy showed increased mural smooth muscle in small airways and alveolar septa, and concentric medial hypertrophy in pulmonary arteries. ARHGAP42 stop-gain variant in the proband leads to exon 5 skipping, and reduced ARHGAP42 levels, which was associated with enhanced RhoA and Cdc42 expression. This is the first report linking a homozygous stop-gain variant in ARHGAP42 with a chILD disorder, systemic hypertension, and immunological findings in human patient. Evidence of smooth muscle hypertrophy on lung biopsy and an increase in RhoA/ROCK signaling in patient cells suggests the potential mechanistic link between ARHGAP42 deficiency and the development of chILD disorder.

Myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN with RS-T) complicated by hyperleukocytosis and gene analysis in relation to leukocytosis

Myelodysplastic/myeloproliferative neoplasm (MDS/MPN) with ring sideroblasts and thrombocytosis (MDS/MPN with RS-T), which exhibits both an increased number of marrow ring sideroblasts and thrombocytosis, is a rare disorder classified as one of the newly established forms of MDS/MPN in the WHO 2016 classification. A 77-year-old female with marked thrombocytosis of 1,024×10⁹/L was tentatively diagnosed with essential thrombocythemia in 2011, and the thrombocytosis was controlled using hydroxycarbamide and low-dose busulfan. In 2016, the leukocyte count increased to a peak value of 68.8×10⁹/L (86.6% mature neutrophils) during platelet-reduction therapy. Bone marrow aspirate exhibited hypercellularity with ring sideroblasts comprising 41.5% erythroblasts without excess myeloblasts. Cytogenetic examination demonstrated the JAK2 V617F mutation and chromosomal abnormality of 46,XX,del(20)(q1?). Furthermore, dysplastic features of erythroid and granuloid precursors, as well as many large atypical megakaryocytes, were observed. Further genetic examinations revealed the SF3B1 K700E mutation, but not amplification of the JAK2 gene or pathogenic mutations in the 13 other genes examined. A diagnosis of MDS/MPN with RS-T was established and hyperleukocytosis was controlled using a higher dose of hydroxycarbamide. Although the patient maintained a stable disease state, she became RBC transfusion-dependent. Hyperleukocytosis, regardless of chemotherapy, is rare and may be novel in this disorder.

Mutant calreticulin knockin mice develop thrombocytosis and myelofibrosis without a stem cell self-renewal advantage

Somatic mutations in the endoplasmic reticulum chaperone calreticulin (CALR) are detected in approximately 40% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). Multiple different mutations have been reported, but all result in a +1-bp frameshift and generate a novel protein C terminus. In this study, we generated a conditional mouse knockin model of the most common CALR mutation, a 52-bp deletion. The mutant novel human C-terminal sequence is integrated into the otherwise intact mouse CALR gene and results in mutant CALR expression under the control of the endogenous mouse locus. CALRdel/+ mice develop a transplantable ET-like disease with marked thrombocytosis, which is associated with increased and morphologically abnormal megakaryocytes and increased numbers of phenotypically defined hematopoietic stem cells (HSCs). Homozygous CALRdel/del mice developed extreme thrombocytosis accompanied by features of MF, including leukocytosis, reduced hematocrit, splenomegaly, and increased bone marrow reticulin. CALRdel/+ HSCs were more proliferative in vitro, but neither CALRdel/+ nor CALRdel/del displayed a competitive transplantation advantage in primary or secondary recipient mice. These results demonstrate the consequences of heterozygous and homozygous CALR mutations and provide a powerful model for dissecting the pathogenesis of CALR-mutant ET and PMF.

Granulocyte colony-stimulating factor-producing pancreatic anaplastic carcinoma in ascitic fluid at initial diagnosis: A case report

Granulocyte colony-stimulating factor (G-CSF)-producing pancreatic tumors are extremely rare. These tumors have an aggressive clinical course and no established treatment. Here, we report an autopsy case of G-CSF-production in pancreatic anaplastic carcinoma (PAC). A 72-year-old woman presented with a large pancreatic head mass and multiple liver metastases. Laboratory data showed leukocytosis (leukocyte count 113.3 × 103 /µL) and high serum G-CSF levels (441 pg/mL; normal range: <39.0 pg/mL). The ascitic fluid was submitted to our pathology laboratory at initial diagnosis. Cytopathology showed that smears from the ascitic fluid were highly cellular and contained numerous malignant cells, mainly in loose groupings. Occasional pseudoglandular formations and giant cells were also present. The malignant cells were round, and no spindle-shaped cells were visible. The nuclei were round to ovoid with coarsely granular chromatin and large prominent nucleoli. Upon immunocytochemistry, tumor cells were positive for G-CSF and vimentin; there was no E-cadherin expression. Histopathological examination of the tumor showed a mixed composition of adenocarcinomatous and sarcomatous regions. Upon immunohistochemistry, both components were positive for G-CSF. Few CD34-positive myeloblasts were observed in the bone marrow. Thus, we diagnosed this as a case of G-CSF production in PAC with leukocytosis. To the best of our knowledge, this is the first report on G-CSF expression immunocytochemically confirmed in PAC. Diagn. Cytopathol. 2017;45:463-467. © 2017 Wiley Periodicals, Inc.

Reactive oxygen species and sperm DNA damage in infertile men presenting with low level leukocytospermia

BACKGROUND

Leukocytes contribute directly and indirectly to reactive oxygen species (ROS) production. Although leukocytospermia is defined as the presence of ≥ 1 × 106 white blood cells/mL (WBC/mL) in a semen sample, the presence of less than 1×10(6) WBC/mL (low-level leukocytospermia) can still produce a detectable amount of ROS, impairing sperm function and lowering the chances of pregnancy. Our objective was to assess the effect of low-level leukocytospermia on semen quality, ROS levels, and DNA damage in infertile men.

METHODS

Semen samples were examined from 472 patients and divided into 3 groups: no seminal leukocytes; group 2, men with low-level leukoctyospermia (0.1-1.0 × 106 WBC/mL); and group 3, frank leukocytospermia, (>1.0 × 106. WBC/mL). Semen analysis, leukoctyospermia, reactive oxygen species and DNA fragmentation was tested.

RESULTS

Conventional semen parameters between the 3 groups were similar. Group 2 patients had significantly higher levels of ROS and sperm DNA fragmentation (1839.65 ± 2173.57RLU/s; DNA damage: 26.47 ± 19.64%) compared with group 1 (ROS: 1101.09 ± 5557.54 RLU/s; DNA damage: 19.89 ± 17.31%) (ROS: p=0.002; DNA damage: p=0.047). There was no significant difference in ROS levels between groups 2 and 3.

CONCLUSIONS

Patients presenting with low-level leukocytospermia have seminal oxidative stress. Although these patients are not categorized as leukocytospermic by current World Health Organization (WHO) guidelines, these men may benefit by treatment with antibiotics, testing for bacterial cultures, or antioxidant supplements to reduce ROS-induced sperm DNA fragmentation and improve their chances of fertility. The WHO guidelines for leukocytospermia may need to be revised accordingly.

The role of therapeutic leukapheresis in hyperleukocytotic AML

PURPOSE

Hyperleukocytosis in AML with leukostasis is a serious life-threatening condition leading to a high early mortality which requires immediate cytoreductive therapy. Therapeutic leukapheresis is currently recommended by the American Society of Apheresis in patients with a WBC>100 G/l with signs of leukostasis, but the role of prophylactic leukapheresis before clinical signs of leukostasis occur is unclear.

PATIENTS

We retrospectively analyzed the role of leukapheresis in 52 patients (median age 60 years) with hyperleukocytotic AML with and without clinical signs of leukostasis. Since leukapheresis was performed more frequently in patients with signs of leukostasis due to the therapeutic policy in our hospital, we developed a risk score for early death within seven days after start of therapy (EDd7) to account for this selection bias and to independently measure the effect of leukapheresis on EDd7.

RESULTS

20 patients received leukapheresis in combination to chemotherapy compared to 32 patients who received chemotherapy only. In a multivariate logistic regression model for the estimation of the probability of EDd7 thromboplastin time and creatinine remained as independent significant parameters and were combined to create an EDd7 risk score. The effect of leukapheresis on EDd7 was evaluated in a bivariate logistic regression together with the risk score. Leukapheresis did not significantly change early mortality in all patients with a WBC≥100 G/l.

DISCUSSION

Prophylactic leukapheresis in hyperleukocytotic patients with and without leukostasis did not improve early mortality in our retrospective study. Larger and prospective clinical trials are needed to validate the risk score and to further explore the role of leukapheresis in AML with hyperleukocytosis.

Nras overexpression results in granulocytosis, T-cell expansion and early lethality in mice

NRAS is a proto-oncogene involved in numerous myeloid malignancies. Here, we report on a mouse line bearing a single retroviral long terminal repeat inserted into Nras. This genetic modification resulted in an increased level of wild type Nras mRNA giving the possibility of studying the function and activation of wild type NRAS. Flow cytometry was used to show a variable but significant increase of immature myeloid cells in spleen and thymus, and of T-cells in the spleen. At an age of one week, homozygous mice began to retard compared to their wild type and heterozygous littermates. Two weeks after birth, animals started to progressively lose weight and die before weaning. Heterozygous mice showed a moderate increase of T-cells and granulocytes but survived to adulthood and were fertile. In homozygous and heterozygous mice Gfi1 and Gcsf mRNA levels were upregulated, possibly explaining the increment in immature myeloid cells detected in these mice. The short latency period indicates that Nras overexpression alone is sufficient to cause dose-dependent granulocytosis and T-cell expansion.

[Sperm mtDNA content and mtDNA4977bp deletion in normal and leukocytospermia men]

OBJECTIVE

To determine the sperm mtDNA content, mtDNA4977bp deletion and ROS in the seminal plasma of normal and leukocytospermia men, and to investigate the correlation of the changes of sperm mtDNA with the increase of leukocytes and reactive oxgygen species (ROS) in the seminal plasma.

METHODS

Seventy-eight semen samples from leukocytospermia patients and 31 from healthy donors were divided into 3 layers, supernatant fluid, 30% sperm and 80% sperm, by Percoll gradient centrifugation, their sperm mtDNA content and mtDNA4977bp deletion quantitatively analyzed by real-time PCR, and the level of ROS determined by flow cytometry.

RESULTS

The ROS in the seminal plasma and the sperm mtDNA contents of the three layers were all significantly higher in the leukocytospermia group than in the healthy control (P < 0.01). In the supernatant fluid and 80% layers, mtDNA4977bp deletion showed no obvious difference between the control and the leukocytospermia group, but was significantly higher in the 30% layer of the latter (P < 0.01). The ROS level was found positively correlated with the mtDNA content in the 30% (r = 0.347, P < 0.01) and the 80% layer (r = 0.456, P < 0.01), but not in the supernatant layer.

CONCLUSION

The increase of leukocytes and ROS may be one of the causes of the enhanced sperm mtDNA content, but has no significant impact on the mtDNA4977bp deletion.

Extreme thrombocytosis associated with transient myeloproliferative disorder with Down Syndrome with t(11;17)(q13;q21)

A female patient with Down Syndrome (DS) had neonatal thrombocytosis with platelet counts exceeding 2,000 x 10(3)/microL and transient myeloproliferative disorder (TMD). Platelet counts remained elevated the first 2 months of life. A translocation located between chromosomes 17 and 11 was observed. We describe a patient with thrombocytosis and TMD showing an 11q13 translocation. The leukocytosis and thrombocytosis improved after an exchange transfusion.

Golgi GDP-fucose Transporter-deficient Mice Mimic Congenital Disorder of Glycosylation IIc/Leukocyte Adhesion Deficiency II

Modification of glycoproteins by the attachment of fucose residues is widely distributed in nature. The importance of fucosylation has recently been underlined by identification of the monogenetic inherited human disease "congenital disorder of glycosylation IIc," also termed "leukocyte adhesion deficiency II." Due to defective Golgi GDP-fucose transporter (SLC35C1) activity, patients show a hypofucosylation of glycoproteins and present clinically with mental and growth retardation, persistent leukocytosis, and severe infections. To investigate effects induced by the loss of fucosylated structures in different organs, we generated a mouse model for the disease by inactivating the Golgi GDP-transporter gene (Slc35c1). Lectin binding studies revealed a tremendous reduction of fucosylated glycoconjugates in tissues and isolated cells from Slc35c1(-/-) mice. Fucose treatment of cells from different organs led to partial normalization of the fucosylation state of glycoproteins, thereby indicating an alternative GDP-fucose transport mechanism. Slc35c1-deficient mice presented with severe growth retardation, elevated postnatal mortality rate, dilatation of lung alveoles, and hypocellular lymph nodes. In vitro and in vivo leukocyte adhesion and rolling assays revealed a severe impairment of P-, E-, and L-selectin ligand function. The diversity of these phenotypic aspects demonstrates the broad general impact of fucosylation in the mammalian organism.

Mast cell-expressed complement receptor, not TLR2, is the main detector of zymosan in peritonitis

The in vitro macrophage response to zymosan has been attributed to Toll-like receptor 2 (TLR2). Whether TLR2 is obligatory for the zymosan-induced in vivo response has not been assessed. The importance of this question is underscored by the fact that zymosan activates complement in a cell-independent manner. We have investigated whether the in vitro observation of TLR2 as the dominant zymosan receptor on macrophages would translate to an experimental peritonitis model in vivo. We have treated mice with zymosan, resulting in significant leukocyte (primarily neutrophil) accumulation in the peritoneum at 4 h. Zymosan-mediated leukocyte recruitment was TLR2 independent, but was predominantly dependent on the complement components, C3 and C5a with a minor contribution from LTB4. Peritoneal neutrophilia was 50% mast cell dependent and this defect was reproduced using C5a receptor (C5aR)-deficient mast cells in mast cell-deficient mice, suggesting that C5aR is responsible for mast cell activation following zymosan challenge. By 24 h, the response to zymosan involved primarily monocyte recruitment and was C3 and C5aR independent. Taken together, these studies indicate that the in vivo inflammatory response to zymosan does not necessarily mimic the TLR2 dependence observed in vitro, and that complement plays a dominant role in early, but not late, zymosan-mediated peritonitis.

A syndrome of holoprosencephaly, recurrent infections, and monocytosis

We describe three siblings with holoprosencephaly, recurrent infections, and increased peripheral blood monocytes. These children were born to apparently healthy parents in a family with one unaffected child. Affected individuals had microcephaly, severe developmental delay, failure to thrive, and brachydactyly. The clinical courses were complicated by endocrine dysfunction, multiple respiratory, and skin infections. Laboratory studies showed normal karyotypes, normal lymphocyte function, and a peripheral blood monocytosis with markedly abnormal morphology. Mutation analysis of the seven genes (SHH, ZIC2, SIX3, TGI, FTDGF1, GLI2, and PTCH) known to be involved in holoprosencephaly was normal. This is the first report demonstrating an association between abnormal mononuclear phagocytes and holoprosencephaly.

Leukocytosis is a risk factor for thrombosis in essential thrombocythemia: interaction with treatment, standard risk factors, and Jak2 mutation status

Leukocytes contribute to the pathogenesis of thrombosis in essential thrombocythemia (ET) through recently discovered mechanisms of activation and interaction with platelets and endothelial cells. To evaluate whether an increased leukocyte count was associated with thrombosis and whether this effect can be modulated by therapy, we analyzed the clinical course of 439 patients with ET followed at the Ospedali Riuniti di Bergamo. The strength of the association was measured at diagnosis or before thrombotic events by multivariable analyses carried out using data at baseline as well as time-varying covariates. The results showed that (1) an increased leukocyte count at diagnosis was associated with thrombosis during follow-up (“baseline analysis,” relative risk [RR] 2.3, 95% confidence interval [CI] 1.4-3.9, P = .001); (2) hydroxyurea (HU) lowered leukocytosis and reduced the strength of the association between leukocytosis and thrombosis (“time-dependent analysis,” RR 1.6, 95% CI 0.9-2.0, not significant [NS]); (3) the association of leukocytosis and thrombosis was more evident in untreated low-risk patients (RR 2.7, 95% CI 1.2-6.4, P = .01) compared with HU-treated high-risk patients (RR 1.6, 95% CI 0.8-3.2, NS); and (4) the presence of JAK2 V617F was not identified as a risk factor for thrombosis during follow-up despite a significant association between the mutation and leukocytosis. We suggest validation of these findings in prospective clinical studies.

Biology, clinical relevance, and molecularly targeted therapy in acute leukemia with FLT3 mutation

Overexpression and activating mutations of receptor tyrosine kinases (RTKs) are known to be involved in the pathophysiology of several kinds of cancer cells. FMS-like receptor tyrosine kinase 3 (FLT3), together with KIT, FMS, and platelet-derived growth factor receptor, is a class III RTK. FLT3 mutations were first reported as internal tandem duplication (FLT3/ITD) of the juxtamembrane domain-coding sequence; subsequently, a missense point mutation at the D835 residue and point mutations, deletions, and insertions in the codons surrounding D835 within a FLT3 tyrosine kinase domain (FLT3/KDMs) have been found. FLT3 mutations are the most frequent genetic alterations so far reported in acute myeloid leukemia and are involved in the signaling pathway of autonomous proliferation and differentiation block in leukemia cells. Several large-scale studies have confirmed that FLT3/ITD is strongly associated with leukocytosis and a poor prognosis. Therefore, routine screening for FLT3 mutations is recommended to stratify patients into distinct risk groups. However, because high-dose chemotherapy and stem cell transplantation cannot overcome the adverse effects of FLT3 mutations, the development of FLT3 kinase inhibitors is expected to produce a more efficacious therapeutic strategy for leukemia therapy.

Prospective study of 174 de novo acute myelogenous leukemias according to the WHO classification: subtypes, cytogenetic features and FLT3 mutations

We report a prospective study of 174 unselected adult de novo acute myeloid leukemia (AML) cases diagnosed using the WHO classification. Of those, 57 (33%) were AML with recurrent cytogenetic abnormalities, 41 were (24%) AML with multilineage dysplasia, 74 (42%) were AML not otherwise categorized, and two were acute leukemias of ambiguous lineage. Clonal cytogenetic abnormalities were detected in 64% of the WHO AML cases with t(15;17) (15%), t(8;21) (12%), +8 (11%), -7/del7q (8%) and del9q (5%) being the most common ones. The FLT3/ITD mutations (FMS-like tyrosine kinase 3/internal tandem duplication) were observed in 12% of the WHO AML cases, which is much lower than ones in the literature, while the 6% incidence of the FLT3-activating loop mutations (either FLT3/D835 or FLT3/I836) was comparable with others. Both mutations were associated with leukocytosis. Our study also suggests that the FLT3 mutations are biomarkers independent of cytogenetic characteristics.

Contribution of NZB Autoimmunity 2 to Y-Linked Autoimmune Acceleration-Induced Monocytosis in Association with Murine Systemic Lupus

The accelerated development of systemic lupus erythematosus (SLE) in BXSB male mice is associated with the presence of the Y-linked autoimmune acceleration (Yaa) mutation, which induces an age-dependent monocytosis. Using a cohort of C57BL/6 (B6) x (NZB x B6)F1 backcross male mice bearing the Yaa mutation, we defined the pathogenic role and genetic basis for Yaa-associated monocytosis. We observed a remarkable correlation of monocytosis with autoantibody production and subsequent development of lethal lupus nephritis, indicating that monocytosis is an additional useful indicator for severe SLE. In addition, we identified an NZB-derived locus on chromosome 1 predisposing to the development of monocytosis, which peaked at Fcgr2b encoding FcgammaRIIB and directly overlapped with the previously identified NZB autoimmunity 2 (Nba2) locus. The contribution of Nba2 to monocytosis was confirmed by the analysis of Yaa-bearing B6 mice congenic for the NZB-Nba2 locus. Finally, we observed a very low-level expression of FcgammaRIIB on macrophages bearing the NZB-type Fcgr2b allele, compared with those bearing the B6-type allele, and the development of monocytosis in FcgammaRIIB haploinsufficient B6 mice carrying the Yaa mutation. These data suggest that the Nba2 locus may play a supplementary role in the pathogenesis of SLE by promoting the development of monocytosis and the activation of effector cells bearing stimulatory FcgammaR, in addition to its implication in the dysregulated activation of autoreactive B cells.

Hereditary haemolytic anaemias: unexpected sequelae of mutations in the genes for erythroid membrane skeletal proteins

Although the haemolytic anaemia may be the primary concern for hereditary spherocytosis and elliptocytosis patients, it is clear that their situation can be compromised by primary and secondary defects in erythroid and non-erythroid systems of the body. All seven of the red cell membrane skeletal proteins discussed in this review are also expressed in non-erythroid tissues, and mutations in their genes have the potential to cause non-erythroid defects. In some instances, such as the protein 4.1R and ANK1 neurological deficits, the diagnosis is clear. In other instances, because of the complex expression patterns involved, the non-erythroid effects may be difficult to assess. An example is the large multidomain, multifunctional band 3 protein. In this case, the location of the mutation can cause defects in one functional domain or isoform and not the other. In other cases, such as the beta-adducin null mutation, other isoforms may partially compensate for the primary deficiency. In such cases, it may be that the effects of the deficit are subtle but could increase under stress or with age. To be completely successful, treatment strategies must address both primary and secondary effects of the anaemia. If gene replacement therapy is to be used, the more that is known about the underlying genetic mechanisms producing the multiple isoforms the better we will be able to design the best replacement gene. The various animal models that are now available should be invaluable in this regard. They continue to contribute to our understanding of both the primary and the secondary effects and their treatment.

Nonmyeloablative Bone Marrow Transplantation of BXSB Lupus Mice Using Fully Matched Allogeneic Donor Cells from Green Fluorescent Protein Transgenic Mice

Male BXSB mice, a mouse model of systemic lupus erythematosus, were given bone marrow transplants (BMT) at 20 wk of age using MHC-matched donor cells and nonmyeloablative conditioning (550 cGy irradiation). Transplanted mice and irradiation controls were followed for a period of 20 wk. Mice transgenic for green fluorescent protein were used as donors to allow tracking of donor cells and a determination of chimerism. Radiation controls had reduced renal pathology at 10 wk posttransplant, but not at 20 wk compared with untreated mice, while nonmyeloablative BMT mice had significantly reduced pathology at both time intervals. The monocytosis characteristic of older BXSB mice was also reduced by BMT, but the treatment did not prevent production of Ab to dsDNA. A stable chimerism of 24-40% donor CD45-positive cells was achieved in spleen and bone marrow, and there was no evidence of clinical graft vs host disease. Donor cells were detected in most recipient organs, notably the thymus and renal glomeruli. The results suggest that complete depletion of mature lymphocytes or of progenitor stem cells is not required to control lupus nephritis in BXSB mice.

Murine γ-Herpesvirus-68-Induced IL-12 Contributes to the Control of Latent Viral Burden, but Also Contributes to Viral-Mediated Leukocytosis

Early IFN-alpha/beta production, followed by the development of a viral-specific CTL response, are critical factors in limiting the level of murine gamma-herpesvirus-68 (gammaHV-68) infection. Development of a long-lived CTL response requires T cell help, and these CTLs most likely function to limit the extent of infection following reactivation. The importance of IL-12 in the development and/or activity of Th1 cells and CTLs is well documented, and we investigated the kinetics and magnitude of gammaHV-68-induced IL-12 production. Following intranasal infection, IL-12 and IL-23 mRNA expression was up-regulated in lung and spleen and lung, respectively, followed by increased levels of IL-12p40 in lung homogenates and sera. Exposure of cultured macrophages or dendritic cells to gammaHV-68 induced secretion of IL-12, suggesting that these cells might be responsible for IL-12 production in vivo. gammaHV-68 infection of mice made genetically deficient in IL-12p40 expression (IL-12p40(-/-)) resulted in a leukocytosis and splenomegaly that was significantly less than that observed in syngeneic C57BL/6 mice. IL-12p40(-/-) mice showed increased levels of infectious virus in the lung, but only at day 9 postinfection. Increased levels of latent virus in the spleen at day 15 postinfection were also observed in IL-12p40(-/-) mice when compared with syngeneic C57BL/6 mice. An overall reduction in gammaHV-68-induced IFN-gamma production was observed in IL-12p40(-/-) mice, suggesting that most of the viral-induced IFN-gamma in C57BL/6 mice was IL-12 dependent. Taken together, these results suggest that gammaHV-68-induced IL-12 contributes to the pathophysiology of viral infection while also functioning to limit viral burden.

Increased resistance of LFA-1-deficient mice to lipopolysaccharide-induced shock/liver injury in the presence of TNF-alpha and IL-12 is mediated by IL-10: a novel role for LFA-1 in the regulation of the proinflammatory and anti-inflammatory cytokine balance

Challenge with low doses of LPS together with D-galactosamine causes severe liver injury, resulting in lethal shock (low dose LPS-induced shock). We examined the role of LFA-1 in low dose LPS-induced shock. LFA-1(-/-) mice were more resistant to low dose LPS-induced shock/liver injury than their heterozygous littermates, although serum levels of TNF-alpha and IL-12 were higher in these mice. C57BL/6 mice were not rescued from lethal effects of LPS by depletion of NK1(+) cells, granulocytes, or macrophages, and susceptibility of NKT cell-deficient mice was comparable to that of controls. High numbers of platelets were detected in the liver of LFA-1(+/-) mice after low dose LPS challenge, whereas liver accumulation of platelets was only marginal in LFA-1(-/-) mice. Following low dose LPS challenge, serum levels of IL-10 were higher in LFA-1(-/-) mice than in LFA-1(+/-) mice, and susceptibility to low dose LPS-induced shock as well as platelet accumulation in the liver of LFA-1(-/-) mice were markedly increased by IL-10 neutralization. Serum levels of IL-10 in LFA-1(+/-) mice were only marginally affected by macrophage depletion. However, in LFA-1(-/-) mice macrophage depletion markedly reduced serum levels of IL-10, and as a corollary, susceptibility of LFA-1(-/-) mice to low dose LPS-induced shock was markedly elevated despite the fact that TNF-alpha levels were also diminished. We conclude that LFA-1 participates in LPS-induced lethal shock/liver injury by regulating IL-10 secretion from macrophages and that IL-10 plays a decisive role in resistance to shock/liver injury. Our data point to a novel role of LFA-1 in control of the proinflammatory/anti-inflammatory cytokine network.

Neutrophilia in LFA-1-deficient mice confers resistance to listeriosis: possible contribution of granulocyte-colony-stimulating factor and IL-17

LFA-1 (CD11a/CD18) plays a crucial role in various inflammatory responses. In this study, we show that LFA-1(-/-) mice are far more resistant to Listeria monocytogenes infection than LFA-1(+/-) mice. Consistent with this, we found the following: 1) the numbers of granulocytes infiltrating the liver were markedly higher in LFA-1(-/-) mice than in LFA-1(+/-) mice, 2) increased antilisterial resistance in LFA-1(-/-) mice was abrogated by depletion of granulocytes, and 3) the numbers of granulocytes in peripheral blood, and the serum levels of both G-CSF and IL-17 were higher in LFA-1(-/-) mice than in LFA-1(+/-) mice. Neither spontaneous apoptosis nor survival of granulocytes from LFA-1(-/-) mice were affected by physiological concentrations of G-CSF. Our data suggest regulatory effects of LFA-1 on G-CSF and IL-17 secretion, and as a corollary on neutrophilia. Consequently, we conclude that increased resistance of LFA-1(-/-) mice to listeriosis is due to neutrophilia facilitating liver infiltration by granulocytes promptly after L. monocytogenes infection, although it is LFA-1 independent.

IL-1 receptor type 1 gene-deficient mice demonstrate an impaired host defense against pneumococcal meningitis

The fatality rate associated with Streptococcus pneumoniae meningitis remains high despite adequate antibiotic treatment. IL-1 is an important proinflammatory cytokine, which is up-regulated in brain tissue after the induction of meningitis. To determine the role of IL-1 in pneumococcal meningitis we induced meningitis by intranasal inoculation with 8 x 10(4) CFU of S. pneumoniae and 180 U of hyaluronidase in IL-1R type I gene-deficient (IL-1R(-/-)) mice and wild-type mice. Meningitis resulted in elevated IL-1alpha and IL-1beta mRNA and protein levels in the brain. The absence of an intact IL-1 signal was associated with a higher susceptibility to develop meningitis. Furthermore, the lack of IL-1 impaired bacterial clearance, as reflected by an increased number of CFU in cerebrospinal fluid of IL-1R(-/-) mice. The characteristic pleocytosis of meningitis was not significantly altered in IL-1R(-/-) mice, but meningitis was associated with lower brain levels of cytokines. The mortality was significantly higher and earlier in the course of the disease in IL-1R(-/-) mice. These results demonstrate that endogenous IL-1 is required for an adequate host defense in pneumococcal meningitis.

Architectural defects in the spleens of Nkx2-3-deficient mice are intrinsic and associated with defects in both B cell maturation and T cell-dependent immune responses

Mice lacking the homeodomain transcription factor Nkx2-3 are either asplenic or develop a spleen of significantly reduced size with poorly organized white pulp. In this report, we analyze the effect of this mutation on B lymphocyte development and differentiation. Follicular dendritic cells in spleen, but not lymph node, of Nkx2-3(-/-) mice fail to express a developmental Ag (follicular dendritic cell-M2) and show an abnormal association with B cells, despite essentially normal expression of several chemokine genes. Bone marrow reconstitution studies show the splenic disorganization and absence of marginal zone B cells to be of stromal rather than hemopoietic origin. Furthermore, Nkx2-3(-/-) mice show an excess of conventional B cells in mesenteric lymph node and peritoneal cavity, whereas transitional B cells are rare in spleen but overrepresented in bone marrow. Finally, immunization of Nkx2-3(-/-) mice with a T cell-dependent Ag elicits clusters of germinal center B cells, although these fail to develop to the same extent as in controls and there is no evidence of affinity maturation in serum Ab. Similarly, Ab-forming cells fail to aggregate into foci early in the response. Collectively, these data indicate a substantial role for Nkx2-3 in the correct association of lymphocytes and splenic stromal elements that is independent of chemokine expression.

Depletion of neutrophils in IL-10(-/-) mice delays clearance of gastric Helicobacter infection and decreases the Th1 immune response to Helicobacter

Gastric infection with Helicobacter induces a lymphocyte-rich mucosal inflammation that contains a minor population of neutrophilic granulocytes. The function of neutrophils in the local immune response to gastric Helicobacter infection remains unknown. To investigate this issue, we conducted experiments in neutrophil-depleted control wild-type (wt) and IL-10(-/-) mice infected with Helicobacter felis by gastric lavage. Infection of wt mice elicited a mild, focal gastritis and a Helicobacter-specific Th1 immune response. In wt mice Helicobacter colonization of the stomach was persistent and progressively increased during the 29 days of observation. Infection of IL-10(-/-) mice with H. felis elicited a severe chronic gastritis and a greatly enhanced Helicobacter-specific Th1 immune response, as compared with wt mice. After initial colonization, the IL-0(-/-) mice completely cleared Helicobacter from the stomach by day 8. The gastric inflammation in wt and IL-10(-/-) mice contained modest numbers of neutrophils. The intensity of gastric inflammation and the extent of Helicobacter colonization were similar in control and in neutrophil-depleted wt mice. In contrast, neutrophil depletion of Helicobacter-infected IL-10(-/-) mice decreased the severity of gastritis, modulated the Helicobacter-specific Th1 immune response, and delayed the clearance of bacteria from the stomach. These studies identify a role for neutrophils in the local and systemic immune response to gastric Helicobacter in IL-10(-/-) mice.

Hyperkeratosis and leukocytosis in transgenic mice carrying MHC class I chain-related gene B (MICB)

Major histocompatibility complex (MHC) class I chain-related gene A and B (MICA and MICB) are located very close to HLA-B. MICA is reported to be strongly associated with Behçet's disease (BD), a multisysytemic inflammation disorder characterized by oral apthous ulcers, skin lesions and genital ulcers. These two molecules are highly conserved at the amino acid levels. To determine the function of MICB in vivo and the relationship between the expression of MICB and BD experimentally, we produced several transgenic mouse lines (termed CAG-MICB) expressing human MICB cDNA under a ubiquitous promoter. They exhibited a 50% increase in the number of white blood cells compared with their non-transgenic littermates, and also exhibited a 10-20% reduction in body weight compared with non-transgenic littermates. Exfoliation of the skin first appeared around 7 days after birth and disappeared after 2 weeks of age. This was repeatedly observed in the transgenic offspring of two independent CAG-MICB lines examined. Histopathological analysis of skin of young mice exhibiting skin abnormalities revealed hyperkeratosis of the epidermis and thickening of the granular layer with slight infiltration of inflammatory cells in the dermis without any vasculitis. Other remarkable abnormalities associated with BD have not been observed in the CAG-MICB lines. Furthermore, fluorescein angiography of eyes of the CAG-MICB lines was performed, but there were no marked changes of BD-related uveitis in the ocular fundus. These findings suggest that (i) MICB expression is related to temporary skin inflammation, and (ii) expression of MICB is not directly associated with BD.

Reduced CTL response and increased viral burden in substance P receptor-deficient mice infected with murine gamma-herpesvirus 68

One component of the protective host response against mucosal pathogens includes the local production and increased expression of certain neuropeptides and their receptors. The present study further demonstrates this fact by investigating the contribution that substance P receptor expression makes toward immunity against a gamma-herpesvirus infection. Following intragastric inoculation with murine gamma-herpesvirus 68 (gamma HV-68), expression of substance P and its receptor was increased in mucosal and peripheral lymphoid organs in wild-type strains of mice. These results suggested that this receptor/ligand pair might be an important component of the host response against this viral infection. Such a hypothesis was supported by the demonstration that mice, genetically deficient in substance P receptor expression, showed an increased viral burden when compared with syngeneic C57BL/6 mice. Furthermore, substance P receptor-deficient mice showed a reduced CTL response against gamma HV-68, suggesting a mechanism to explain this increased viral burden. Such limitations in the Ag-specific CTL response in substance P receptor-deficient mice could result from lowered expression of IL-12 during viral infection. Consistent with this hypothesis, increases in mRNA encoding IL-12 and secretion of this cytokine into sera of infected, wild-type animals were markedly reduced in substance P receptor-deficient mice. These studies demonstrate that genetic elimination of substance P receptors in mice results in an increased gamma-herpesvirus burden and an altered host response.

Conditional control of selectin ligand expression and global fucosylation events in mice with a targeted mutation at the FX locus

Glycoprotein fucosylation enables fringe-dependent modulation of signal transduction by Notch transmembrane receptors, contributes to selectin-dependent leukocyte trafficking, and is faulty in leukocyte adhesion deficiency (LAD) type II, also known as congenital disorder of glycosylation (CDG)-IIc, a rare human disorder characterized by psychomotor defects, developmental abnormalities, and leukocyte adhesion defects. We report here that mice with an induced null mutation in the FX locus, which encodes an enzyme in the de novo pathway for GDP-fucose synthesis, exhibit a virtually complete deficiency of cellular fucosylation, and variable frequency of intrauterine demise determined by parental FX genotype. Live-born FX(-/-) mice exhibit postnatal failure to thrive that is suppressed with a fucose-supplemented diet. FX(-/-) adults suffer from an extreme neutrophilia, myeloproliferation, and absence of leukocyte selectin ligand expression reminiscent of LAD-II/CDG-IIc. Contingent restoration of leukocyte and endothelial selectin ligand expression, general cellular fucosylation, and normal postnatal physiology is achieved by modulating dietary fucose to supply a salvage pathway for GDP-fucose synthesis. Conditional control of fucosylation in FX(-/-) mice identifies cellular fucosylation events as essential concomitants to fertility, early growth and development, and leukocyte adhesion.

New IL-17 family members promote Th1 or Th2 responses in the lung: in vivo function of the novel cytokine IL-25

We have biologically characterized two new members of the IL-17 cytokine family: IL-17F and IL-25. In contrast to conventional in vitro screening approaches, we have characterized the activity of these new molecules by direct in vivo analysis and have compared their function to that of other IL-17 family members. Intranasal administration of adenovirus expressing IL-17, IL-17C, or IL-17F resulted in bronchoalveolar lavage neutrophilia and inflammatory gene expression in the lung. In contrast, intranasal administration of IL-25-expressing adenovirus or IL-25 protein resulted in the production of IL-4, IL-5, IL-13, and eotaxin mRNA in the lung and marked eosinophilia in the bronchoalveolar lavage and lung tissue. Mice given intranasal IL-25 also developed epithelial cell hyperplasia, increased mucus secretion, and airway hyperreactivity. IL-25 gene expression was detected following Aspergillus and Nippostrongylus infection in the lung and gut, respectively. IL-25-induced eosinophilia required IL-5 and IL-13, but not IL-4 or T cells. Following IL-25 administration, the IL-5(+) staining cells were CD45R/B220(+), Thy-1(+/-), but were NK1.1-, Ly-6G(GR-1)-, CD4-, CD3-, and c-kit-negative. gamma-common knockout mice did not develop eosinophilia in response to IL-25, nor were IL-5(+) cells detected. These findings suggest the existence of a previously unrecognized cell population that may initiate Th2-like responses by responding to IL-25 in vivo. Further, these data demonstrate the heterogeneity of function within the IL-17 cytokine family and suggest that IL-25 may be an important mediator of allergic disease via production of IL-4, IL-5, IL-13, and eotaxin.

Establishment and characterization of a new lung cancer cell line (MI-4) producing high levels of granulocyte colony stimulating factor

We established a human lung cancer cell line, MI-4 from the pleural effusion of a 69-year-old male with advanced large cell undifferentiated carcinoma of the lung complicated by leukocytosis. The culture supernatant of MI-4 contained high levels of granulocyte colony stimulating factor (G-CSF). The intracellular localization of the G-CSF was identified by immunocytochemistry. Reverse transcription-polymerase chain reaction (RT-PCR) revealed G-CSF mRNA expression in this cell line. The cell line was successfully transplanted into nude mice. The transplanted nude mice also showed leukocytosis with a high serum G-CSF level. Southern blot analysis did not show amplification or rearrangement of the G-CSF gene in MI-4 cells. Spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) analyses revealed that this cell line has an additional chromosome 17 attached to a segment of chromosome 10 besides two intact chromosomes 17, and that each of these three chromosomes 17 has a G-CSF gene on chromosome 17q. Inflammatory cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, significantly enhanced G-CSF expression at both the protein and mRNA levels in MI-4. However, these cytokines did not stimulate the growth of MI-4 cells, regardless of abundant G-CSF production. TNF-alpha rather suppressed it, in a dose-dependent manner. Exogenous recombinant human G-CSF and anti-G-CSF antibody did not promote or inhibit the growth of MI-4 cells at any concentration examined. In addition, RT-PCR analysis did not show G-CSF receptor mRNA expression. These results suggest that this cell line does not have an autocrine growth loop for G-CSF. This cell line should be very useful for understanding the biological activity of G-CSF in G-CSF-overproducing lung cancer.

Forced expression of murine IL-17E induces growth retardation, jaundice, a Th2-biased response, and multiorgan inflammation in mice

IL-17 is a proinflammatory cytokine, and its in vivo expression induces neutrophilia in mice. IL-17E is a recently described member of an emerging family of IL-17-related cytokines. IL-17E has been shown to bind IL-17Rh1, a protein distantly related to the IL-17R, suggesting that IL-17E probably possesses unique biological functions. In this study, we have identified the murine ortholog of IL-17E and developed transgenic mice to characterize its actions in vivo. Biological consequences of overexpression of murine (m)IL-17E, both unique to IL-17E and similar to IL-17, were revealed. Exposure to mIL-17E resulted in a Th2-biased response, characterized by eosinophilia, increased serum IgE and IgG1, and a Th2 cytokine profile including elevated serum levels of IL-13 and IL-5 and elevated gene expression of IL-4, IL-5, IL-10, and IL-13 was observed in many tissues. Increased gene expression of IFN-gamma in several tissues and elevated serum TNF-alpha were also noted. In addition, IL-17E induces G-CSF production in vitro and mIL-17E-transgenic mice had increased serum G-CSF and exhibit neutrophilia, a property shared by IL-17. Moreover, exposure to mIL-17E elicited pathological changes in multiple tissues, particularly liver, heart, and lungs, characterized by mixed inflammatory cell infiltration, epithelial hyperplasia, and hypertrophy. Taken together, these findings suggest that IL-17E is a unique pleiotropic cytokine and may be an important mediator of inflammatory and immune responses.

Regulated control by granulocyte-macrophage colony-stimulating factor AU-rich element during mouse embryogenesis

In vitro studies have indicated that the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression is regulated at the posttranscriptional level by the AU-rich element (ARE) sequence present in its 3' untranslated region (UTR). This study investigated the importance of the ARE in the control of GM-CSF gene expression in vivo. For this purpose, transgenic mice bearing GM-CSF gene constructs containing or lacking the ARE (GM-CSF AU(+) or GM-CSF AU(-), respectively) were generated. Both transgenes were under the transcriptional control of the immediate early promoter of the cytomegalovirus (CMV) to ensure their early, widespread, and constitutive expression. The regulation imposed by the ARE was revealed by comparing transgene expression at day 14 of embryonic development (E14); only the ARE-deleted but not the ARE-containing construct was expressed. Although GM-CSF AU(+) embryos were phenotypically normal, overexpression of GM-CSF in E14 GM-CSF AU(-) embryos led to severe hematopoietic alterations such as abnormal proliferation of granulocytes and macrophages accompanied by an increased number of peroxidase-expressing cells, their putative progenitor cells. These abnormalities compromise development because no viable GM-CSF AU(-) transgenic pups could be obtained. Surprisingly, by E18, significant accumulation of transgene messenger RNA was also observed in GM-CSF AU(+) embryos leading to similar phenotypic abnormalities. Altogether, these observations reveal that GM-CSF ARE is a developmentally controlled regulatory element and highlight the consequences of GM-CSF overexpression on myeloid cell proliferation and differentiation.

The role of alpha beta+ T cells and homeostatic T cell proliferation in Y-chromosome-associated murine lupus

Male BXSB mice develop an early life, severe lupus-like disease largely attributed to an undefined Y-chromosome-associated autoimmunity accelerator, termed YAA: Although the exact disease pathogenesis is uncertain, indirect evidence suggests that T cells play an important role in the male BXSB disease. We have developed TCR alpha-chain gene-deleted BXSB mice to directly examine the role of alphabeta+ T cells and the mode by which Yaa promotes disease in this strain. All disease parameters, including hypergammaglobulinemia, autoantibody production, glomerulonephritis, and the unique monocytosis of BXSB males, were severely reduced or absent in the alphabeta+ T cell-deficient mice. Adoptively transferred CD4+ T cells of either male or female BXSB origin showed equal homeostatic proliferation in alphabeta+ T cell-deficient male recipients. Moreover, deficient male mice eventually developed equally severe lupus-like disease after adoptive transfer and homeostatic expansion of T cells from wild-type BXSB males or females. The results directly demonstrate that the Yaa-mediated disease requires alphabeta+ T cells that are not, in themselves, abnormal in either composition or properties, but are engaged by a Yaa-encoded abnormality in a non-T cell component. In addition, homeostatic anti-self proliferation of mature T cells derived from a small number of precursors can induce systemic autoimmunity in an appropriate background.

A genetic model of stress displays decreased lymphocytes and impaired antibody responses without altered susceptibility to Streptococcus pneumoniae

Stress pathways affect immune function, the most notable of these pathways being activation of the hypothalamic-pituitary-adrenal (HPA) axis. Although HPA activation has generally been relegated to an immunosuppressive role, recent evidence suggests that stress and HPA activation can be immunoenhancing in certain situations. To investigate specific effects of stress on immune function, we used a genetic model of chronic stress wherein transgenic mice overexpress corticotropin-releasing hormone (CRH), a primary mediator of the stress response. In these mice, CRH is overproduced in the brain, leading to chronic activation of the HPA axis. We found that CRH-transgenic mice have decreased leukocyte numbers in lymphoid compartments, with preferential loss of B lymphocytes. They also exhibit decreased Ab production and impaired isotype switching in response to immunization with a thymus-dependent Ag, phosphocholine-keyhole limpet hemocyanin. Despite these deficits, immunization protected CRH-transgenic and wild-type mice equally well against lethal challenge with Streptococcus pneumoniae, an encapsulated Gram-positive bacterium known to require Ab-mediated opsonization for clearance. While IgG responses are severely depressed in these mice, IgM titers are only modestly decreased. This fairly robust IgM response may be sufficient to protect against S. pneumoniae. Additionally, while total leukocyte numbers are decreased in these mice, neutrophil numbers are increased. This increase in number of neutrophils may compensate for the depressed IgG response, allowing adequate host defense during chronic stress.

The myeloma-associated oncogene fibroblast growth factor receptor 3 is transforming in hematopoietic cells

Translocations involving fibroblast growth factor receptor 3 (fgfr3) have been identified in about 25% of patients with myeloma. To directly examine the oncogenic potential of fgfr3, murine bone marrow (BM) cells were transduced with retroviral vectors containing either wild-type fgfr3 or an activated mutant form of the receptor, fgfr3-TD. Mice transplanted with FGFR3-TD-expressing BM developed a marked leukocytosis and lethal hematopoietic cell infiltration of multiple tissues within 6 weeks of transplantation. Secondary and tertiary recipients of spleen or BM from primary fgfr3-TD mice also developed tumors within 6 to 8 weeks. Analysis of the circulating tumor cells revealed a pre-B-cell phenotype in most mice, although immature T-lymphoid or mature myeloid populations also predominated in some animals. Enhanced lymphoid but not myeloid colony formation was observed in the early posttransplantation period and only interleukin 7 and FGF-responsive pre-B-cell lines could be established from tumors. Cell expansions in primary recipients appeared polyclonal, whereas tumors in later passages exhibited either clonal B- or T-cell receptor gene rearrangements. Mice transplanted with wild-type FGFR3-expressing BM developed delayed pro-B-cell lymphoma/leukemias approximately 1 year after transplantation. These studies confirm that FGFR3 is transforming and can produce lymphoid malignancies in mice.

The accumulation of dendritic cells in the lung is impaired in CD18-/- but not in ICAM-1-/- mutant mice

Bone marrow-derived dendritic cell (DC) precursors migrate via the blood stream to peripheral tissues to adopt their sentinel function. To identify factors facilitating their emigration to the lung, mutant mice deficient in E-selectin, P-selectin, E/P-selectin, ICAM-1, or CD18 and their respective controls were examined. DCs and monocytes/macrophages were immunolabeled with M5/114 and MOMA-2 mAbs, respectively, and quantified morphometrically. Of these genotypes, the numbers of DC and MOMA-2+ cells were significantly less only in the lungs of CD18-/- mice by 68 and 35% in alveolar walls and by 28 and 26% in venous walls, respectively. DCs were reduced by 30 and 41% around large and small airways, respectively, but the number of MOMA-2+ cells in these locations was not significantly different from controls. Ablation of a single gene may be associated with augmented expression of other, related gene products. Therefore, we examined the expression of VCAM-1. Increased numbers of arteries exhibited continuous luminal VCAM-1 staining in both CD18-/- and ICAM-1-/- mutants. VCAM-1 expression was absent in pulmonary capillaries and unchanged in veins. These data suggest that under nonperturbing conditions, CD18-mediated adhesion is required for the full complement of DC precursors to accumulate in the lungs. However, the defect in CD18-/- mice is partial, suggesting that CD18-independent adhesion occurs. The alternative pathway may involve VLA-4/VCAM-1 in arteries and venules but not in capillaries. The smaller defect in ICAM-1-/- mice suggests that the CD11/CD18 complex recognizes ligands other than ICAM-1 at some sites.

Evaluation of RNA isolation methods and reference genes for RT-PCR analyses of rare target RNA

Reverse transcription polymerase chain reaction (RT-PCR) analysis is increasingly becoming part of the diagnostic and prognostic evaluation for hematologic and oncologic disorders. Currently, different RNA isolation methods are used in the diagnostic laboratories. No data are available on their suitability for sensitive detection of breakpoint cluster region-abelson (BCR-ABL) gene transcripts. We have extracted RNA from mononuclear cell (MNC) fractions and from lysed blood samples of 4 patients (1 with leukocytosis, 1 with chronic myelogeneous leukemia (CML) under interferon treatment, and 2 CML patients after bone marrow transplantation) with 3 RNA isolation reagents (TRIzol, RNAzol, FastTube reagent). RNA yield was slightly higher with RNAzol than with TRIzol as indicated by agarose gel electrophoresis and spectrophotometric measurement at 260 nm. The FastTube reagent was unsuitable for RNA isolation from MNC, and was not evaluated for lysed blood. Quantitative competitive RT-PCR amplification of the ABL gene showed comparable results for RNA isolated with RNAzol and TRIzol. In RNA samples extracted from lysed whole blood, the presence of amplifiable RNA/cDNA was confirmed by amplification of 4 selected reference genes (porphobilinogen deaminase (PBGD), ABL, the gene spanning the BCR on chromosome 22 and retinoic acid receptor alpha (RARA)) in a multiplex PCR. High quality, DNA-free RNA was obtained with RNAzol, and 1 BCR-ABL-positive (specific for translocation t [9; 221) cell among 2x10(4) normal cells was successfully detectable by single step RT-PCR. In RNA isolated with TRIzol, major contaminations with genomic DNA were observed which significantly impaired the interpretation of the results of RT-PCR analysis.

Clonality analysis using X-chromosome inactivation at the human androgen receptor gene (Humara). Evaluation of large cohorts of patients with chronic myeloproliferative diseases, secondary neutrophilia, and reactive thrombocytosis

Chronic myeloproliferative diseases (MPDs) are not associated with consistent cytogenetic or molecular abnormalities. Demonstration of clonal cell growth by analysis of X-chromosome inactivation (XCI) patterns in females provides a promising tool for diagnosis. However, this technique can be complicated by excessive lyonization of normal cells mimicking clonal cell growth: We analyzed XCI patterns at the human androgen receptor (HUMARA) locus in 146 healthy females, 65 women with secondary neutrophilia, 31 women with reactive thrombocytosis, and 86 women with chronic MPDs. A skewed XCI pattern with greater than 75% amplification of 1 allele (allele ratio > 3:1) was found in 22 (9.1%) of 242 control subjects. The incidence of skewing was statistically significantly lower in women younger than 30 years (2/73) compared with women older than 60 years (10/53). Of 86 patients with a chronic MPD, 71 (82%) exhibited an allele ratio greater than 3:1, whereas only 10 (12%) of 86 age-matched control subjects showed a skewed XCI pattern. Although statistical evaluation of the data showed a significant difference between patients with a chronic MPD and control subjects, proof of clonality in individual, especially elderly, patients is difficult.

Cloning, biological characterization and high-level expression of rat interleukin-3 using recombinant adenovirus: description of a new splicing variant

In the present study, we describe the cloning and sequence analysis of rat IL-3. Two different mRNA isoforms were isolated after transfection of COS cells with the cytokine genomic sequences. One of the isoforms has been predicted before by Cohen et al. (1986), and the other one is identical except that it encodes a protein with an insertion of three amino acids at position 56. As names for the two isoforms, we propose IL-3alpha for the predicted and IL-3beta for the novel molecule. IL-3beta mRNA was detected as the predominant isoform in rat lymphocytes in vivo. High levels of the cytokine were obtained after infection of human cells (A549) with a recombinant adenovirus harboring rIL-3beta cDNA (IG.Ad.CMV.IL-3beta). The biological properties of the IL-3beta protein were tested in a FDC-P1 proliferation assay and in a hematopoietic progenitor colony forming assay. To assess in-vivo bioactivity, lysed 293 cells containing IG.Ad.CMV.rIL-3beta virus were injected subcutaneously into F344 rats. Stimulation of hematopoiesis and leucocytosis were observed during the treatment. After subcutaneous injections of the lysed adeno-producer cells in mice, the only effect observed was a cellular infiltration at the site of injection, confirming the poor cross-reactivity between the two species. The biological properties in vitro and in vivo demonstrate that the cDNA sequences of IL-3beta presented here encode active rat IL-3 protein.

The molecular basis of leukocytosis

The function of any known gene is often found by DNA or protein homology scanning. Conversely, it is equally rewarding to search for the genetic basis behind a known function. Here, Ghislain Opdenakker and colleagues examine the known and possible novel genes and molecular events underlying the phenomenon of leukocytosis, one of the most common clinical manifestations of inflammatory problems.

Neutrophil emigration in the skin, lungs, and peritoneum: different requirements for CD11/CD18 revealed by CD18-deficient mice

To determine the role of CD11/CD18 complexes in neutrophil emigration, inflammation was induced in the skin, lungs, or peritoneum of mutant mice deficient in CD18 (CD18-/- mutants). Peripheral blood of CD18-/- mutants contained 11-fold more neutrophils than did blood of wild-type (WT) mice. During irritant dermatitis induced by topical application of croton oil, the number of emigrated neutrophils in histological sections of dermis was 98% less in CD18-/- mutants than in WT mice. During Streptococcus pneumoniae pneumonia, neutrophil emigration in CD18-/- mutants was not reduced. These data are consistent with expectations based on studies using blocking antibodies to inhibit CD11/CD18 complexes, and on observations of humans lacking CD11/CD18 complexes. The number of emigrated neutrophils in lung sections during Escherichia coli pneumonia, or in peritoneal lavage fluid after 4 h of S. pneumoniae peritonitis, was not reduced in CD18-/- mutants, but rather was greater than the WT values (240 +/- 30 and 220 +/- 30% WT, respectively). Also, there was no inhibition of neutrophil emigration during sterile peritonitis induced by intraperitoneal injection of thioglycollate (90 +/- 20% WT). These data contrast with expectations. Whereas CD11/CD18 complexes are essential to the dermal emigration of neutrophils during acute dermatitis, CD18-/- mutant mice demonstrate surprising alternative pathways for neutrophil emigration during pneumonia or peritonitis.